I. Definitions
As used herein, the phrase “group III-V” refers to a compound semiconductor that includes a group V element and at least one group III element. Moreover, the phrase “III-Nitride” refers to a compound semiconductor that includes nitrogen (N) and at least one group III element, including aluminum (Al), gallium (Ga), indium (In), and boron (B), and including but not limited to any of its alloys, such as aluminum gallium nitride (AlxGa(1-x)N), indium gallium nitride (InyGa(1-y)N), aluminum indium gallium nitride (AlxInyGa(1-x-y)N), gallium arsenide phosphide nitride (GaAsaPbN(1-a-b)), and aluminum indium gallium arsenide phosphide nitride (AlxInyGa(1-x-y)AsaPbN(1-a-b)), for example. III-Nitride also refers generally to any polarity including but not limited to Ga-polar, N-polar, semi-polar or non-polar crystal orientations. A III-Nitride material may also include either the Wurtzitic, Zincblende, or mixed polytypes, and may include single-crystal, monocrystalline, polycrystalline, or amorphous structures.
II. Background Art
Group III-V heterostructure field-effect transistors (group III-V HFETs), such as group III-V high electron mobility transistors (group III-V HEMTs), are often utilized in high power switching applications. For example, III-Nitride HEMTs may be utilized to provide switching and/or amplification functions.
Group III-V HFETs advantageously allow implementation of power transistors using a lateral conduction topology in which the drain, source, and gate electrodes are formed on one side of a semiconductor wafer or die. In a typical lateral transistor layout, for example, drain and source finger electrodes coupled to respective drain and source pads may be interdigitated and surrounded by a gate region. As the power requirement for such transistors continues to increase, the transistors are fabricated with a higher unit cell density. However, due to high termination electric fields typically present at the drain finger electrode ends, the gate-to-drain spacing at the drain finger electrode ends of higher density power transistors may be insufficient to reliably sustain a high breakdown voltage.